Markey reacted to a story in last Saturday's New York Times examining how the online advertising industry is now able to track consumers across the various platforms and devices they use, often without the user's knowledge or consent.

That Times' scoop followed an Oct. 2 report about how the National Security Agency conducted a secret pilot program in 2010 and 2011 to test the collection of bulk data about the location of Americans' cell phones. That pilot program was never carried out.

Even so, Markey said in a statement issued late Thursday to reporters that he is "concerned about the increasing practice of marketers scooping up digital traces from our phones, tablets and computers that are then stitched together into detailed dossiers without consumers' knowledge or permission."

In a separate -- but very much related development on Thursday -- data management firm Identity Finder disclosed how the caching mechanism in Google's popular Chrome browser stores unencrypted personal data in a way that makes it trivial for hackers to steal.

If privacy is the gunpowder in these developments, consumer trust is the fuse. For most of the past dozen years, U.S.consumers have extended Google, Microsoft, Yahoo, Apple, Facebook, AOL, Verizon and AT&T a high level of trust as the tech giants went about devising infrastructure to collect vast amounts of data on how we use phone and Internet services.

Led by Google and Facebook, the online advertising industry should hit a record $40 billion in revenue this year by intensively data mining information culled from our Internet searches and web surfing. Contacts, interests and preferences we disclose in our web browsers and on our smartphone apps routinely gets co-mingled with personal disclosures made on popular social networks.

Online display, mobile and search ads should top a record $40 billion this year(Photo: Interactive Advertising Bureau)

All of this tracking and profiling is in the service of delivering what the ad industry asserts is more relevant ads. By and large this is done without asking permission. All of this was just fine with the majority of U.S. consumers -- until Edward Snowden came along.

Snowden's disclosures of the NSA's PRISM surveillance program revealed the extent to which the tech giants turn over some of this sensitive consumer data over to government snoops. Snowden's whistleblowing -- and the surge of investigative reporting that has followed -- has given Americans an impetus to question online tracking, more along the lines of what Europeans have been doing for years.

The realization that the federal government has been tapping into the advertising industry's tracking data -- arguably with good reason: to track and deter terrorists -- has prompted consumers in both the U.S. and Europe to consider how to exert more individual control over what ought to stay private.

Make no mistake, the richest players in the online advertising industry desire no changes in the rules of how the game is played.Online ad sales rose 18% in the first six months of this year to $20.1 billion, and should easily top $40 billion by the time we get through Christmas sales, according to Interactive Advertising Bureau.

Over the past two years, Google and Facebook have poured millions into lobbying efforts to derail proposed federal Do Not Track regulations. And last month, the ad industry quietly stifled an earnest effort by the respected World Wide Web Consortium (W3C) to establish voluntary Do Not Track standards, something the W3C had optimistically hoped to get done by the summer of 2013.

Sen. Markey has long championed the concerns of privacy advocates. In his letter to FTC Chairwoman Edith Ramirez, Markey writes: "Such tracking envelopes users in a digital environment where marketers know their preferences and personal information no matter which device they use while consumers are kept largely in the dark. I request that the Commission investigate this emerging tracking trend."